The present invention relates to a power supply voltage stabilizing method, a semiconductor device, and a power supply system suitable for a battery, and relates to, for example, a power supply voltage stabilizing method for a battery mounted in an automobile and the like.
A battery is mounted in, for example, an automobile, and electricity fed from the battery to a cell motor for starting an engine, an engine controller (hereinafter, referred to as an ECU), and the like. Various types of electronic devices are mounted in the ECU. A battery voltage from the battery is stabilized by a power supply circuit such as a switching power supply, a stabilized output voltage is fed from the power supply circuit to the electronic devices mounted in the ECU, and the electronic devices are operated using the fed output voltage as a power supply voltage.
In order to realize the stabilized output voltage, the switching power supply includes a voltage feedback unit that feeds back the output voltage of the switching power supply to a switching control unit, and a current feedback unit that stabilizes the output voltage at a high speed. The switching power supply is described in, for example, Japanese Unexamined Patent Application Publication No. 2011-101479 and Japanese Unexamined Patent Application Publication No. 2011-97434.